Deflection system



April 8, 1958 K. SCHLESINGER 2,830,228

DEFLECTION SYSTEM Filed May 5, 1955 2 Sheets-Sheet 1 n ,1 FW

. l 6 l 5 I/ 27 IN VEN TOR. [far 5 fcklesi zger BY Wu Z April 8, 1958 K. SCHLESINGER 2,830,228

DEFLECIION SYSTEM Filed May 5, 1955 I 2 Sheets-Sheet 2 Lll IN V EN TOR.

United States Patent nunrnorroist SYSTEM Kurt Schlesinger, La Grange, Illi, assignor to Motorola,

Inc, Chicago, Ill., acorporation of Illinois Application May 5, 19'55', Serial-No. 506,203

6 (Elai'ms. or. MEL-2'4).

Thisrinvention. relates to beam deflection apparatus for" cathode ray' tubes. and more. particularly to electrostatic deflection. systems: using: electrodes positioned in circular form: for bidirectional deflection of. electron' beams.

Thedeflectiom s-ystenr ofi this. invention isan improvement. of the system disclosed and claimed in application 1 Serial No: 361,472, filed June F5; 1953, now Patent #12,770;748" in the names of Kurt Schlesinger and Victor Graziano.

. the system above referred toperforms satisfactorily, spacing of the electrodes which is necessary for insulating purposesmay have aslightd-istorting effect on the'defiection field's due to=tl1e presence of chargesbuilt up on the supportform for the electrodes.

An object. of this invention is to provide a beam defleetion device of circular form. which corrects nonuniiormity in the deflection fields caused by the spacing of the. electrodes.

Another object of the invention is to provide a biaxial electrostatic deflection system wherein ahigh degree of linearity is obtained. in the system using electrodes positioned in circular configuration.

Another object is to provide a sensitive electrostatic beam deflection system in which a minimum of distortion is produced in the various deflected positions of th beam. i p

A feature of. the invention is a provision of a beam deflecting. system including an insulating. member having a circular section supporting zigzag interleaved electrodes which extend substantially 270* about the insulating member are angularly spaced thereabout for insulation purposes The electrodes have-portions of increased area alongya boundary thereof at 90 positions around the insulating member to correct for field nonuniformities caused by the spacing of the. electrodes.- 7 p Another feature is the provision of electrostatic beam electrostatic beam deflection apparatusv including an insul'ati-ng member of conical or cylindrical form for supportingaseries of interleaved zigzag conductors spaced angular-1y about the member and having. complementary edge portions of sinusoidal configuration and in which the edge portions are iurtherconstructed to have a configuration of the secondharmonicofthe aforementioned sinusoidal"configuration thereby increasing the nfective a 2,830,228 Patented Apr. 8, 1958 2 area of the conductor along an'axis of deflection of the beam tominimize deflection. distortion.

Further objects, features. and the attending advantages thereof willbe apparent upon consideration of the following description when taken in conjunction with the ac companying drawing in which:

Fig. I; shows a cathode ray tubehaving deflection electrodes of: circular shape;

Fig. 2. is. a. development of. a pattern of the electrodes for use. on 3:. circular support form;

. Fig;.3- illustrates a. practical embodiment'of the of Fig. 2;

Figs. 4 and 5 illustrate-modifications of the pattern of' Fig. 3 in accordance with the present invention;

Fig. 6 and 7 show the compensated pattern of the invention as; usedain connectionzwith a conical support form;

Fig-8. illustrates the deflection apparatus of the present invention mounted in a cathode ray tube.

This invention; provides compensation or correction in an electrostatic beam deflection device so that a more uniform deflection field is produced. The beam is passed through. a circular insulating form on which is disposed a set of electrodes in zigzag interleaved fashion circumfercntially. of the form and running axially along the form. The electrodes have complementary sinusoidal configurations and subtend an angle of substantially 270 circumpattern 7 ferentially of the insulating form. The conductors are spaced from. one another by a given angular amount around the form for insulating. purposes. Such spacing introduces. some variation in the beam deflection field due to the. build-up of an electrical charge between the electrodes. Accordingly, at least one boundary line between electrodesisaltered to change the area of the electrode at 90 positions. about the form in order to compensate for these. spurious. charges. To furnish a suitable correcting. field, the. electrodes may include small, rounded extensions at the beam entrance and exit ends of the form. Or, a further correcting structure may consist of constructing the complementary edges. of the conductors in a sinusoidal manner. at the second. harmonic of the sinusoidal configuration above mentioned tozincrease the electrode area along the axes of deflection of the beam for providing. correction of the deflection field.

In Fig. 1, there is shown a cathode ray tube 10 having an electrostatic deflection structure 11. The tube includes an electron gun 12 which directs a beam of electrons through the structure 11. Structure. 11 comprises a tubular supporting member 13 which may be made of glass (transparent), ceramic, orthe like, and which has electrically conductive coatings or electrodes 14 on the inside surfaces thereof. Member 13 may be either cylindrical or conical and reference willbe made herein, to

ing potential for the electron beam may be provided by connectionto one. or more anodes 19 ings on the inside of the tube 10.

Fig. 2 shows a development of the pattern of the electrodes shown in- Fig. l and the horizontal direction corresponds to the circumference while the vertical represents the longitude of structure 11. It may be seen that four electrodes are provided, and these are designated 24, 25', 26' and 271 Electrodes 24 and 27 have portions at both ends of the pattern. All of these electrodes are of identical configuration, and they are symmetrically positioned, with the apex portions interleaved with one another. Electrode 21, will now be described in detailand the description. will suflice for all the electrodes since they are'identical.

provided as coat- Electrode 25 is composed of four sections designated 25a, 25b, 25c and 25d with adjacent ones extending in opposite directions. Section 25a is bounded by two parallel sides 28, 29, each of which extends a distance corresponding to 90 in the circular form of the structure and sides 28, 29 are spaced from one another by 90. Sides 31, 32 of section 25a are of sinusoidal configuration and represent one-half of a sine wave, and these sides join the parallel sides 28, 29. Sides 31, 32 are alike, and are spaced in the horizontal direction in Fig. 2, that is, the circumferential extent in a completed form of the electrode. Since the sinusoidal sides 31, 32 have a circumferential length corresponding to an angle of 180 and the sides 28, 29 subtend an angle of 90, section 25a has an over-all circumferential extent of 270.

It can be proved both mathematically and in practice that the electrodes having the configuration of section 2511 produce a field as though they extended 180, 90 on either side of line 35, and provide a field distribution which would be obtained by a section varying sinusoidally in the horizontal or circumferential direction. Since sections 25a-d are of the same configuration, except that every other section extends in the opposite direction, and since they are all interconnected, they will be at the same potential and will make similar contributions to the over-all field.

Of course, in actual practice, electrical connection will be made to a point on each of the electrodes 24--27 which will then be operated at'different potentials so that insulation between the electrodes is necessary. Fig. 3 shows section 252 in greater detail and shows suitable spacing of the electrodes as they are supported on the member 13 to provide insulation. It may be seen that the electrode configurations shown in Fig; 3 are similar to those of Fig. 2, except that the spacing of the electrodes has been represented by the angle d. This is a constant angular spacing which may be of the order of -15 depending on the voltages in the circuit. This spacing provides necessary insulation between the electrodes without, however, effecting the distribution of the field produced by the electrodes.

The pattern described for the electrostatic deflection electrodes would produce the required uniform fields if there were no effect produced by the charge which accumulates in the spacing between the electrodes. In a structure for use at high voltages where substantial spacing must be provided between the electrodes, the fields resulting from charges on the glass or ceramic supporting member between the electrodes is substantial. This results in an alteration of the field at various points around the electrode structure. By summing the fields at various points of the pattern as shown in Fig. 3, it

may be found that the summation of the length and poin which Y is the wave length of one section, n is the total number of sections'used per electrode, a is the angular position of the point considered, d is the spacing angle between electrodes, and w represents the sweep frequency.

It has been found that correction for the above error and the beam distortion produced thereby can be obtained in two manners. One method consists in providingaseries of four digits-across the gaps-at each of the extremeboundaries of the electrodes at the beam entrance and exit portions of the structure so. that correcting fields are produced by adjacent electrodes'to reduce 4 the field produced by the electrodes along the diagonals of deflection. Fig. 4 illustrates digits 43, 44, 45 and 46 and associated respectively with electrodes 24-27. Each digit has a shape represented by the following equation:

Z= A Yn (l-cos d) where Z is the thickness of the digit, Y is the wave length of one electrode section, It is the total number of sections per electrode and d is the angular spacing between electrodes. Digits 47-50 are provided at the other ends of the electrodes although any odd number of sections may be used with such digits. It may be seen that electrode in Fig. 4 extends substantially 135 on either side of center line 59 which may form an axis of deflection. Therefore, since the digits are spaced by approximately 90, the digits at the ends of each electrode are substantially 45 from the center line of the adjacent electrode. The digits then provide correcting fields to reduce the field produced by an adjacent electrode at diagonals to the beam deflection axes, the axes being in the planes formed by the two sets of electrode center lines.

Fig. 6 shows an application of the digits which provide field correction in a pattern including three sections in each electrode suitable for use on a conical form.

" Digits 5154 are provided at the beam exit end of the structure and digits 55-58 are provided at the beam entrance end of the structure.

Ditficulty may be experienced with this arrangement in some applications, since it is necessary to provide a conductive bridge from the electrodes to the digits to make an electrical connection to the digit. This is illustrated by the bridge 62 connecting digit 45 to electrode 25 in Fig. 4. These conductive bridges may cause some error or distortion in the pattern of the deflection field.

Fig. 5 illustrates the construction of the electrodes in accordance with a second approach to the problem of correcting distortion caused by a charge accumulating in the spacing between the electrodes. In this approach a second harmonic is superimposed on the sinusoidal boundary curves to increase the fields along the axes of deflection. In the construction of Fig. 3, the center line of the spacing btween electrodes 24 and 25 may be represented by the equation: /2(1cos a), where a is the angular position of the point considered. However, in the construction of Fig. 5, the center line 32' between electrodes 24 and 25 now conforms to the modified equation l 2(1cos aK sin 2a). The center line 32' therefore takes the form of a second harmonic configuration superimposed on top of the original sinusoidal configuration of one-half of a sine wave. The electrode edges are equally spaced on each side of the center line as in the prior embodiments. Accordingly the area of each electrode is increased somewhat along each electrode center line, thus strengthening the fields along the deflection axes.

Fig. 7 illustrates a pattern 65 consisting of four electrode sections which may be supported on a conical form. In practice, it has been found that a construction such as shown in Fig. 7, while only an approximate solution to the distortion problem in terms of mathematics, provides very satisfactory deflection field with the distortion reduced to less than 3%. This operation is very satisfactory for many types of applications.

Fig. 8 illustrates a cut-away view of the cathode ray tube 10 with the electron gun 12 which directs a beam through the conical support member 70. The member may be composed of glass to form a suitable insulating member upon the inside of which is positioned an electrode structure 74, which corresponds to the pattern shown in Fig. 7. 4

The electrode structure disclosed can be used in many diiferent'applications. In order to provide radial sweep,

v sinusoidal voltage waves, displ'acedin phase by 90 can be applied to opposi'tepairs of electrodest Accordingly, this invention. provides an improvedelectrostatic deflection structure which maybe supported on a cylindrical or conical insulating form' to provide desired deflection for use in television receivers, radar equipment and other like applications. The structure provides a deflection system of great sensitivity, since all of the assumes electrodes are used in deflection in each direction, and

since almost the entire supporting form is occupied by the conducting electrodes. Furthermore, a large portion of any distortion introduced into the system by electric charges on the necessary spacing between the electrodes is compensated by the electrode construction described above so that there is a minium of distortion in the system and excellent circularity is obtained.

I claim:

1. An electrode structure for providing electrostatic deflection of a cathode ray beam including, an insulating tubular support member having an opening therein through which the beam passes, four conducting electrodes symmetrically positioned with respect to each other on the surface of said support member, each of said electrodes extending longitudinally of said tubular member and being of zigzag shape with apex portions extending in opposite directions around said tubular member from center portions thereof and having an angular extent in each direction from said center portions of substantially 135, said electrodes being interleaved and angularly spaced on said surface and adjacent electrodes having spaced opposed edges of complementary substantially sinusoidal configuration, so that an electric potential produced by application of a voltage between alternate electrodes has an etfective angular extent of 180 and a substantially sinusoidal distribution, the areas of said electrodes being constructed so that the electric fields produced by said center portions of alternate electrodes is increased with respect to the electric fields produced by portions spaced by 45 from said center portions, to provide correction for field irregularity due to an electric charge on said support member in the spacing between said electrodes.

2. An electrode structure for providing electrostatic defiection of a cathode ray beam including, an insulating tubular support member having an opening therein through which the beam passes, four conducting electrodes symmetrically positioned with respect to each other on the surface of said support member, each of said electrodes extending longitudinally of said tubular member and being of zigzag shape with apex portions extending in opposite directions around said tubular member from perpendicular axes of the structure and having angular extents in each direction from an axis of substantially 135, said electrodes being interleaved and angularly spaced on said surface and adjacent electrodes having spaced opposed edges of complementary substantially sinusoidal configuration, so that an electric potential produced by application of a voltage between alternate electrodes covers effectively 180 of the periphery of said support member and has a substantially sinusoidal distribution thereover, the areas of said electrodes being constructed so that the fields along said axes are in-' creased with respect to the fields between said axes, to provide correction for field irregularity due to an electric charge on said support member in the spacing between said electrodes.

3. An electrode structure for providing electrostatic deflection of a cathode ray beam including, an electrically insulating tubular support member having an opening therein through which the beam passes, four conducting electrodes symmetrically positioned with respect to each other on the surface of said support member, each of said electrodes extending longitudinally of said tubular member and being of zigzag shape with apex portions extending in opposite directions around said tubular member? and having an over-all angular. extent there'- about of substantially 270, said' electrodes being inter.- leaved and angularly spaced" on said surface and adjacent electrodes'having spaced opposed edges' of complementary substantially sinusoidal configuration, said electrodes having portions of increased area at angular positions about said structure spaced by substantially 90 so-thatan electric potential produced by application of a voltage between alternate electrodes has an effective angular extent of 180 and a sinusoidal distribution, with said portions of increased area providing correction for field irregularity due to charges on said support member in the spaces between said electrodes.

4. An electrode structure for providing electrostatic deflection of a cathode ray beam including, four conducting electrodes symmetrically positioned with respect to 7 each other in circular relation about a beam path, each of said electrodes extending longitudinally of said beam path and being of zigzag shape with apex portions extending in opposite directions around said beam path from center portions thereof and having an angular extent in each direction from said center portions of substantially 135", said electrodes being interleaved and angularly spaced and adjacent electrodes having spaced opposed edges of complementary substantially sinusoidal configuration, so that an electric potential produced by application of a voltage between alternate electrodes has an effective angular extent of 180 and a substantially sinusoidal distribution throughout such extent, the area of said electrode being constructed so that the field produced at said center portions of alternate electrodes is increased with respect to the fields produced at portions spaced by from said center portions, to provide correction for field irregularity due to the spacing of said electrodes.

5. An electrode structure for providing electrostatic deflection of a cathode ray beam including, an insulating tubular support member having an opening therein through which the beam passes, four conducting electrodes symmetrically positioned with respect to each other on the surface of said support member, each of said electrodes extending from respective beginning and end points longitudinally along said tubular member and being of zigzag shape with apex portions extending in opposite directions around said tubular member and having an over-all angular extent thereabout of substantially 270, said electrodes being angularly spaced and interleaved to provide a substantially continuous conducting coating on said surface and adjacent electrodes having spaced opposed edges of complementary sinusoidal configuration, so that an electric potential produced by application of a voltage between alternate electrodes has an effective angular extent of 180 and a substantially sinusoidal distribution through such extent, and digit portions at said beginning and end points of said electrodes, said digit portions providing correction fields spaced at 90 intervals for cancelling portions of the fields produced by electrodes adjacent each digit portion to provide a uniform field about said electrode structure.

6. An electrode structure for providing electrostatic deflection of a cathode ray beam including, an electrically insulating tubular support member having an opening therein through which the beam passes, four conducting configuration, so that an electric potential produced by application of a voltage between alternate electrodes has an effective angular extent of 180 and a substantially sinusoidal distribution throughout such extent, with said portions of second harmonic configuration providing correction for field irregularity due to an electric charge on said support member between said electrodes.

a 7 References Cited in the file of this patent UNITED STATES PATENTS p 5 Von Ardenne May 18, 1937 Vo'n Ardenne' Jan. 2, 1940 Schlesinger Nov. 4, 1952 Schlesinger Nov. 4, 1952 Schlesinger June '15, 1954 

